Aluminum base alloy containing zirconium-chromium-manganese



June 4, 1968 G. J. JAGACIAK 3,386,820

ALUMINUM BASE ALLOY CONTAINING ZIRCONIUM-CHROMIUM-MANGANESE Filed Jan. 26, 1966 2 Sheets-Sheet 1 "J A 8 ME mos E k fi 65E 3 Q f cs5 Q v 3:5 &

700 A/VNEAL/NG TEMPERATURE ('F) I; 9, v a a Q Isa (0001 X) Hi QNJUJS (773M INVENTOR. 6ORG J.JAGAC/AK A TTORNEY United States Patent 3,386,820 ALUMINUM BASE ALLGY CONTAINING ZIRCONIUM-CHROMIUM-MANGANESE George J. Jagaciak, Milford, Conm, assignor to Olin Mathieson Chemical Corporation, a corporation of Virginia Filed Jan. 26, 1966, Ser. No. 523,073 3 Claims. (Cl. 75-138) The present invention relates to aluminum base alloys having high thermal stability. More particularly, the present invention resides in aluminum base alloys containing zirconium, chromium and manganese.

Commercially available wrought aluminum base alloys generally recrystallize in a temperature range of 550 to 700 F. It is, naturally, highly desirable to develop aluminum alloys with higher recrystallization temperatures since, in general, the higher the recrystallization temperature the more resistant the alloy is to softening at elevated temperatures.

Although, the recrystallization temperature of a given alloy is dependent upon alloying additions, the mechanism of recrystallization itself is not well understood. In particular, the roll of precipitate morphology versus solid solution effects in inhibiting the recrystallization process are not readily separable. It is agreed, however, that a coarse second phase precipitate is not effective in raising the recrystallization temperature, that is, if one uses alloying additions that coarsen readily, for example, silicon, magnesium or silicon plus magnesium, the recrystallization temperature is not altered significantly.

It is highly desirable to develop aluminum base alloys having a higher recrystallization temperature or softening temperature than presently available. This is illustrated in Table I below which shows the typical ambient temperature yield strengths for a number of commercially available alloys annealed bet-ween thirty minutes and ten hours at the given temperatures. The outstanding alloy in this series is aluminum alloy 21219, a well known elevated temperature aluminum alloy, Even this alloy loses the bulk of its strength between 600 and 700 F.

3,386,820 Patented June 4, 1968 It has been found that the foregoing alloy readily achieves the objects of the present invention.

Recrystallization temperature of aluminum alloys can be raised by producing a fine dispersion of precipitates stable at high temperatures. Zirconium, chromium and manganese form stable precipitates in aluminum at elevated temperature and furthermore, because the atomic mobilities of these elements in aluminum are low, these precipitates do not coarsen below about 800 F.

In accordance with the present invention the preferred ranges of alloying additions are as follows: the preferred zirconium range is from 0.3 to 0.5%; the preferred chromium range is from 0.2 to 0.3%; and the preferred manganese range is from 0.5 to l.'3%.

In addition, a considerable advantage of the present invention is that commercial purity aluminum may be readily utilized. In general, the alloy of the present invention may contain the following impurities: iron, up to 0.7%; silicon, up to 0.2%; copper, up to 0.2%; others, each up to 031%, total up to 0.25%.

The present invention will be more readily apparent from a consideration of the following illustrative examples.

EXAMPLE -I An ingot was cast having a size 5" high by 4" wide by 1%" thick. The ingot was cast at 1300 F. using the Durville casting method. The nominal composition was: zirconium, 0.45%; chromium, 0.25%; manganese, 0.5%;

balance essentially aluminum. Theresulting ingot was scalped on both fiat surfaces. Subsequent to scalping, the as-cast ingot was hot rolled at 650 :F. to 0.086 gage.

The hot rolling was followed by 30% cold reduction to.

EXAMPLE II This example utilizes the as cold rolled sheet as in TABLE I.EFFECT OF HIGH TEMPERATURE EXPOSURE ON AMBIENT TEMPERATURE YIELD STRENGTH OF SEVERAL ALUMINUM-BASE ALLOYS Yield Strength (p.s.l.) After Exposure to Annealing Temperature Aluminum Association Room Tern- 300 F. 500 F. 600 F. 700 F. 800 F. 900 F.

Alloy No. perature Accordingly, it is an object of the present invention to develop an improved aluminum base alloy.

It is a further object of the present invention to develop an aluminum base alloy having high thermal stability.

It is an additional object of the present invention to provide an aluminum base alloy as aforesaid having a high recrystallization temperature or softening temperature and in addition having a relatively low cost.

Further objects and advantages of the present invention will appear hereinafter.

In accordance with the present invention it has now been found that the foregoing objects and advantages may be readily obtained and an improved aluminum base alloy provided.

The alloy of the present invention consists essentially of the following: zirconium from 0.2 to 0.7%; chromium from 0.1 to 0.35%; manganese from 0.3 to 1.5%; balance essentially aluminum.

Example I. To corroborate the findings of Example I, the as cold rolled sheet prepared in Example I was resolutionized at 1150 F. for four hours, cold rolled 30% to 0.042 and annealed for thirty minutes at temperatures from 500 to 900 F. Room temperature hardness measurements were made on specimens annealed at various temperatures and are plotted in FIGURE 2. FIGURE 2 clearly shows agreement with the results given in FIGURE 1 in that the alloy again did not begin to soften prior to 800 F.

Metallographic analyses indicate that the formation of a 'very fine precipitate of ZrAl and CrAl is a significant factor that contributes to the surprising stability of this alloy at elevated temperatures.

This invention may be embodied in other forms or carried out in other ways Without departing from the spirit or essential characteristics therof. The present embodiment is therefore to be considered as in all respects 3 illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and all changes which come within the meaning and range of equivalency are intended to be embraced therein.

What is claimed is:

1. An aluminum base alloy consisting essentially of Zirconium from 0.2 to 0.7% by Weight; chromium from 0.1 to 0.35% by Weight; manganese from 0.3 to 1.5% by Weight; baalnce essentially aluminum.

2. An aluminum base alloy according to claim 1 wherein the zirconium is present in an amount from 0.3 to 0.5% by weight, the chromium is present in an amount from 0.2 to 0.3% by weight, and the manganese is present in an amount from 0.5 to 1.3% by weight,

taining iron up to 0.7% by weight, silicon up to 0.2% by weight, copper up to 0.2% by weight, others each up to 0.1%, total up to 0.25%.

References Cited UNITED STATES PATENTS HYLAND B IZOT, Primary Examiner.

3. An aluminum base alloy according to claim 1 con- 15 RICHARD O. DEAN, Examiner. 

1. AN ALUMINUM BASE ALLOY CONSISTING ESSENTIALLY OF ZIRCONIUM FROM 0.2 TO 0.7% BY WEIGHT; CHROMIUM FROM 0.1 TO 0.35% TO WEIGHT; MANGANESE FROM 0.3 TO 1.5% BY WEIGHT; BALANCE ESSENTIALLY ALUMINUM. 